Motor vehicle with a supporting structure of light alloy

ABSTRACT

A motor-vehicle, particularly an electrically-powered car of small size, has a supporting structure in the form of a reticular framework ( 2 ) of light alloy. The framework ( 2 ) includes two side structures ( 3 ) each formed by extruded profile elements ( 4 ) which are welded to joining knot elements ( 5 ) which have been obtained by casting. The side structures ( 3 ) are connected to each other by cross members ( 6, 7, 8, 9 ) which also are formed by extruded profile elements having their ends connected to the side structures ( 3 ) by mechanical coupling means, such as screws.

BACKGROUND OF THE INVENTION

The present invention relates to a motor-vehicle of the type comprising:

a supporting structure formed by a reticular framework of light alloy,

said reticular framework including two side structures each formed byextruded profile elements welded to joining knot elements which havebeen obtained by casting,

said side structures being connected to each other by cross memberswhich are also formed by extruded profile elements having their endsconnected to said side structures by mechanical coupling means.

A motor-vehicle of this type is disclosed in European Patent ApplicationEP-A-0 146 716.

SUMMARY OF THE INVENTION

The object of the invention is to provide a new structure for amotor-vehicle of this type which is characterized by a number ofrelevant advantages, such as a relatively reduced weight, a reducednumber of components and an increase of the torsional rigidity of thestructure.

A further object of the invention is that of providing a newmotor-vehicle structure which can be manufactured with technologieswhich require low investments, so as to provide an adequate responseeven to a market of reduced size.

In view of achieving these objects, the invention provides amotor-vehicle of the above indicated type, wherein said motor-vehiclehas an electric power unit and said reticular framework is connected toa floor panel of composite plastic material including a longitudinalcentral tunnel-like portion, said tunnel-shaped housing thereunderelectric batteries for supplying the electric power unit of themotor-vehicle, and

wherein said electric power unit forms part of a preassembled power andsuspension unit including:

a supporting cross member, formed by an extruded metal profile fixed bymechanical coupling means to the supporting structure of themotor-vehicle,

a pair of longitudinal arms pivotally connected to the cross memberaround a common axis parallel to the longitudinal direction of saidcross member , by supports fixed to the cross member, said arms havingfree ends on which there are rotatably mounted respective wheelsupports,

a power unit supported in a cantilever fashion by the cross member by asupporting beam fixed to the cross member and including two axles shaftsconnected to said wheel supports to transfer thereto the torquegenerated by the power unit, and

a pair of suspension members comprising a damping cylinder and a helicalspring respectively interposed between the two longitudinal arms and tworespective supports fixed to the cross member.

Due to the above indicated features, the motor-vehicle according to theinvention achieves a number of important advantages. First of all, thestructure is comprised of an extremely reduced number of components,which renders the assembling and maintenance operations dramaticallysimpler and cheaper. Even the weight of the structure is greatly reduced(approximately by 30%) with respect to a conventional structure of amotor-vehicle of the same category, the whole with a relevant increase(approximately by 20%) of the torsional rigidity. The technologiesinvolved for the manufacture require low plant investments, so that themotor-vehicle is particularly suitable even to a production in arelatively reduced quantity. The power and suspension unit can bepre-assembled and then mounted with easy and rapid operations on thesupporting structure of the motor-vehicle. This unit can also bedismantled with similarly simple operations in order to allowmaintenance and registering operations to be carried out on thesuspension and the power unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparentfrom the description which follows with reference to the annexeddrawings, given purely by way of non limiting example, in which:

FIG. 1 is a diagrammatic perspective view of a preferred embodiment ofthe motor-vehicle according to the invention,

FIG. 2 is a perspective view at an enlarged scale of the supportingstructure of the motor-vehicle of FIG. 1,

FIG. 3 is an exploded perspective view of the structure of FIG. 2,

FIG. 4 is an exploded perspective view at an enlarged scale of a sidedoor of the motor-vehicle of FIG. 1,

FIG. 5 is a perspective view which shows the supporting structure of themotor-vehicle of FIG. 1, with the preassembled power and suspensionunit,

FIG. 6 is perspective exploded view of the unit shown in FIG. 5,

FIG. 7 is a cross-sectional view of a detail of FIG. 6,

FIG. 8 is a perspective view of a preferred embodiment of the floorpanel of the motor-vehicle according to the invention,

FIG. 9 is a cross-sectional view taken along line IX—IX of FIG. 9,

FIG. 10 is a diagrammatic perspective view of the floor panel of themotor-vehicle, with a part of the device for guiding and supporting theseats mounted thereon,

FIG. 11 is a plan diagrammatic view of the passenger compartment of themotor-vehicle of FIG. 1, and

FIG. 12 is a cross-sectional view taken along line XII—XII of FIG. 12.

FIG. 1 shows an electrically-powered car of small size, for which theapplicants have devised a preferred embodiment of the invention.However, it is clearly apparent that the invention is generallyapplicable to any type of motor-vehicle structure. In FIG. 1, referencenumeral 1 generally designates the electrically powered car, which has asupporting structure generally designated by 2 in FIG. 2. Structure 2 ismade of light alloy and comprises (see also FIG. 3) two side structures3 each formed by extruded profile element 4 connected by welding toconnector elements 5 of light alloy which have been obtained by casting.The two side structures 3 are connected to each other by cross members6, 7, 8, 9 which also are formed by extruded profile elements of lightalloy, which have their ends connected to the side structures 3 bymechanical coupling means, such as screws, and if necessary also byadhesive. As shown in FIGS. 2, 3, the reticular framework 2 is formed bya reduced number of parts and does not include elements which extendrearwardly of the rear beams of the side doors and rearwardly of thecross member 6 which connects the lower ends of these beams. This crossmember is also used, as will be described hereinafter, has a supportingelement for a sub-assembly which includes the power unit and the rearsuspension of the motor-vehicle.

As also shown in FIGS. 2, 3, the reticular structure 2 is connected bymechanical coupling means (screws or rivets) and adhesive to a floorpanel 10, preferably made of composite material, including a centrallongitudinal tunnel-like portion 11 which is used to receive thereunderelectric batteries 12 carried by a tray-shaped element 13, thesebatteries serving for supplying the electric motor with which themotor-vehicle is provided. The floor panel of composite material ispreferably made embedding therein the electric wires forming part of theelectric system, as also shown hereinafter. Furthermore, said centrallongitudinal tunnel-like portion 11 may be used also as a supportingelement for further components, such as particularly the guides of thefront seats, which are supported in a cantilever fashion by said centrallongitudinal tunnel-like portion so as to leave the space under eachseat easily accessible also laterally from outside, as also will bedescribed hereinafter.

The body of the motor-vehicle comprises panels of composite material 14,some of which are shown in the drawings, which are connected bymechanical coupling means (screws or rivets) and/or adhesive to thereticular structure 2.

FIG. 4 shows the structure of a side door of the motor-vehicle whichalso includes a frame of light alloy 15 formed by extruded and bentprofile elements made of light alloy and an outer panel 16 and innerpanel 17 of composite material which are connected, e.g. by screwsand/or adhesive, to frame 15. Frame 15 may be used to support theweather strips guiding the window pane, the sealing strips, theconventional anti-intrusion bar and the door lock and the door hinges.The inner panel 17 of polymeric composite material is adapted to supportthe mechanisms for driving the pane and opening the door, as well as theinner upholstery. This configuration has relevant advantages withrespect to reduced weight, reduced number of components, low cost ofproduction, easy integration of the accessories within the components ofcomposite material, and easy manufacture of the outer and inner shapeseven if very complicated. The use of panels of plastic material,finally, eliminates the corrosion problems.

With reference to FIGS. 5-7, cross member 6 is used for supporting apreassembled power and rear suspension unit of the motor-vehicle. Thesupporting cross member 6 has slots 6 a with a T-shaped cross sectionwhich receive the heads of screws for fixing the ends of the crossmember 6 to the supporting structure 2, as well as for fixing of thefurther components of the power and rear suspension unit, which isgenerally designated by reference numeral 18. Cross member 6 is furtherprovided with two end covering plates 6 b (FIG. 6). The unit 18 furtherincludes two longitudinal arms 19, forming part of the rear suspensionof the motor-vehicle, each having at one end two legs 19 a each endingwith a fork 20 for articulation of the supporting cross member 6 arounda common articulation axis 21 (FIG. 5) parallel to the longitudinaldirection of cross member 6, i.e. transverse relative to thelongitudinal direction of the motor-vehicle. Forks 20 are articulated tocross member 6 by articulation supports 22 which are screwed to thecross member 6.

Arms 19 have free ends which rotatably support respective wheel supports23.

Reference numeral 24 generally designates the power unit which, in theillustrated example, comprises an electric motor 25 and a reducing gearunit 26 from which two axle shafts 27 project which are connected byconventional universal joints to the wheel supports 23 so as to transmitthe torque generated by the power unit 24 to the wheels. This unit isfixed to a supporting beam 28 which on its turn is screwed to thesupporting cross member 6, so that the power unit 24 is supported in acantilever fashion by cross member 6, rearwardly of the latter, withreference to the direction of movement of the motor-vehicle, indicatedby arrow A in FIG. 5. The rear suspension further includes twosuspension members 29 each comprising a damping cylinder 30 and ahelical spring 31. Each of these members is interposed between a support32 carried by the respective arm 19 and a support 33 screwed to thesupporting beam 6.

As it is clearly apparent from the foregoing description, the whole unit18 can be preassembled and then mounted with a single operation onto thesupporting structure of the motor-vehicle, in a simple and rapid way.Similarly, it can be dismantled to allow maintenance or registeringoperations.

Naturally, the use of a modular unit of the type described above alsoenables the production to be rationalized, for example by adopting thesame module for vehicles of different size. As already indicated, theonly connection of the unit to the supporting structure of the vehicleis represented by the mechanical coupling means at the ends of thesupporting cross member 6, which renders the assembling and dismantlingoperations extremely simple and rapid. Although, as already indicated,the invention is applicable to any type of motor-vehicle, itsapplication to the car which has been described in the foregoing givesraise to further advantages, due to the extremely simple and hence cheapconfiguration of the supporting structure of the vehicle.

With reference to FIGS. 8, 9, the floor panel 10 of the motor-vehiclehas a sandwich-like structure (FIG. 9) comprising a core 34 of foamedplastic material, preferably polyurethane material, coated on its twoopposite sides with a preformed layer 35 of fibre glass. To obtain thissandwich-like structure, there is provided a mould having aconfiguration corresponding to the floor panel to be obtained on which afirst preformed layer 35 is deposited, followed by the preformedpolyurethane foam 34 and the second layer 35. The mould is closed and athermosetting polyester resin is injected, such as resin “Aropol 7343”by Ashland Chemical Inc. Inside the mould metal inserts 13 are providedeach comprising a tubular cylindrical body 37 whose axis 38 isorthogonal the plane of the floor panel and extends throughout the wholethickness of the floor panel, with two end disks 39, 40. The tubularbody 37 has a cylindrical hole for engagement of screws for fixingfurther elements (not shown) to the floor panel.

According to the invention, during the manufacturing process of thefloor panel, inside the mould there are also provided the electric wireswhich are to connect the electric supply batteries to the electric motorof the car, as well as the various control devices with which the car isprovided. This electric wires, designated in FIG. 8 by reference numeral42, preferably have no insulating sheath, since this function isfulfilled by the structure itself of the floor panel. As shown in FIG.2, the terminals of the various electric wires project out of the floorpanel, to be connected to respective connectors. However, it isnaturally possible that also these connectors, to which the terminals ofelectric wires 42 are connected, be embedded within the floor panel.

With reference to FIGS. 10-12, the floor panel 10 of the motor-vehiclehas a central longitudinal tunnel-like portion 11 comprising asubstantially horizontal upper wall 43 and two substantially verticalside walls 44.

The embodiment which is illustrated herein refers to a car with only twoside doors, having two front seats 45, 47 and two rear seats 48. Each ofthe two front seats 45, 47 is mounted on an auxiliary supportingstructure 49, preferably made of magnesium alloy, which is supported ina cantilever fashion by the respective side wall 44 of the longitudinalcentral tunnel-like portion 11 of the floor panel 10 of themotor-vehicle. On each side wall 44 there are fixed two guide rails 50,51 (FIG. 12) arranged along two longitudinal parallel directions whichare spaced apart from each other vertically. On these guide rails 50, 51there are slidably mounted cooperating guide skids which are associatedwith the auxiliary supporting structure 49, so as to render the positionof the seat with respect to the floor panel 10 of the motor-vehicleadjustable along the longitudinal direction of the motor-vehicle.

The details of construction of the guide rails 50, 51 and the respectiveskids are not shown herein, since these details may be made in any knownway and do not fall, taken alone, within the scope of the presentinvention. The same applies to the device for locking the seat in theselected longitudinal position, which also can be provided in any knownway. Also in this case, therefore, these details have not been shown,since they do not fall within the scope of the invention and theirdeletion from the drawings renders the latter easier to understand. Asit is clearly apparent from FIGS. 10, 12, due to the above describedarrangement, the space under the seat is completely free both forplacing objects in it and for inserting the feet by the passengersseated on the rear seat. When the front seats are in their forward mostposition with the backrest tilted forwardly, to enable the passengers toget on and off the rear seats, the floor panel does not present anyobstacle to the passengers. Furthermore, the portion of the floor panelunder the seat is completely relieved from loads and stresses. Finally,since the auxiliary supporting structure 7 is mounted in a cantileverfashion on tunnel 3, the space under the seat is completely opened onits side facing outwardly of the motor-vehicle so as to be easilyaccessible also laterally.

According to further preferred (although not essential) features, theseat 45 has its frame mounted on the auxiliary supporting structure 49so as to be rotatable around a vertical axis 46, to allow a 90° rotationof the seat outwardly of the motor-vehicle so as to make easier for thepassenger to get on and off. In a possible variant, the seat frame isfurther mounted on the auxiliary supporting structure 49 with theinterposition of guide means which allow the seat to be displacedlaterally outwardly to make further easy for the passenger to get on andoff the seat.

As it is clearly apparent from the foregoing description, the deviceaccording to the invention for supporting and guiding the front seatscan be provided in a simple and inexpensive way, is reliable inoperation and solves efficiently all the drawbacks of the prior artwhich have been described.

Naturally, while the principle of the invention remains the same, thedetails of construction and the embodiments may widely vary with respectto what has been described and illustrated purely by way of example,without departing from the scope of the present invention.

What is claimed is:
 1. Motor-vehicle, comprising: a supporting structureformed by a reticular framework (2) of light alloy, said reticularframework (2) including two side structures (3) each formed by extrudedprofile elements (4) welded to cast connector elements (5), said sidestructures (3) being connected to each other by cross members (6, 7, 8,9) which are also formed by extruded profile elements having their endsconnected to said side structures (3) by mechanical coupling means,wherein said motor-vehicle has an electric power unit and said reticularframework (2) is connected to a floor panel of composite plasticmaterial (10) including a longitudinal central tunnel-shaped portion(11), said tunnel-shaped portion (11) housing hereunder electricbatteries (12) for supplying the electric power mit of themotor-vehicle, and wherein said electric power unit forms part of apreassembled power and suspension unit (18) including: a supportingcross member (6), formed by an extruded metal profile fixed bymechanical coupling means to the supporting structure (2) of themotor-vehicle, a pair of longitudinal arms (19) pivotally connected tothe cross member (6) around a common axis (21) parallel to alongitudinal direction of said supporting cross member (6), said arms(19) having free ends on which there are rotatably mounted respectivewheel supports (23), said electric power unit (24) supported in acantilever fashion by the supporting cross member (6) by a supportingbeam (28) fixed to the supporting cross member (6) and including twoaxle shafts (27) connected to said wheel supports (23) to transferthereto torque generated by the electric power unit (24), and a pair ofsuspension members (29) comprising a damping cylinder (30) and a helicalspring (31) respectively interposed between the two longitudinal arms(19) and two respective supports (33) fixed to the supporting crossmember (6).
 2. Motor-vehicle according to claim 1, characterized in thatthe electric power unit (24) is formed by an electric motor (25) and agear reducing unit (26).
 3. Motor-vehicle according to claim 1,characterized in that the supports (22) to which the longitudinal arms(19) are articulated, the beam (28) supporting the electric power unit(24) and the supports (33) for the suspension members (29) are all fixedto the supporting cross member (6) by screws.
 4. Motor-vehicle accordingto claim 1, characterized in that the supporting cross member (6) isfixed at its ends to the supporting structure (2) of the motor-vehicleby screws.
 5. Motor-vehicle according to claim 1, characterized in thatthe supporting cross member (6) is an extruded profile of aluminiumalloy.
 6. Motor-vehicle according to claim 1, characterized in that thesupporting cross member (6) supporting the preassembled unit (18)connects said two side frame structures (3) forming part of the vehiclesupporting structure (2) at lower rear connector elements thereof. 7.Motor-vehicle according to claim 1, characterized in that said floor ofcomposite plastic material (10) has a plurality of electric wires (42)embedded therein, said electric wires (42) having no insulating sheathand having terminals connected to electric connectors which are alsoembedded within the structure of the floor panel (10) and project atleast partially from the surface of the floor panel.
 8. Motor-vehicleaccording to claim 7, characterized in that in said floor panel (10)there are embedded metal inserts (36) each having an axial hole (41)extending throughout the whole thickness of the panel, for engagement ofscrews for fixing further elements to the floor panel (10). 9.Motor-vehicle according to claim 1, wherein a substantially verticalside wall (44) of said longitudinal tunnel-shaped portion (11) has guiderails (50, 51) directed along two parallel longitudinal directions whichare vertically spaced apart from each other, and a seat frame issupported in a cantilever fashion by said vertical wall (44) through anauxiliary supporting structure (49) which is slidably mounted on saidrails (50,51).
 10. Motor-vehicle according to claim 9, characterized inthat the seat frame is mounted on said auxiliary supporting structure(49) with the interposition of further guide means which enable the seat(45) to be displaced laterally outwardly of the motor-vehicle, to makeit easier for a passenger getting on and off the seat.
 11. Motor-vehicleaccording to claim 1, characterized in that it has a body comprisingpanels of composite plastic material (14) connected to said reticularstructure (2).